| 摘要 |
PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery in which the lowering of cycle capacity is small at a high temperature and which has excellent storage performance by replacing Mn with transition metals selected from Co, Ni, Fe, V, Cr and Ti in the surface of a positive electrode active material. SOLUTION: A positive electrode active material used for a nonaqueous electrolyte secondary battery, in the surface, is a spinel lithium manganese oxide in which Mn is replaced with at least either one transition metal selected from Co, Ni, Fe, V, Cr and Ti. Almost all parts except the surface are formed of LiMn2 O4 . It is preferable that the molar fraction of Mn and transition metals is 0.99:0.01 to 0.8:0.2. The positive electrode active material is obtained by dispersing a manganese dioxide into an aqueous solution in which the salt of transition metals is dissolved and adjusting it to the alkaline side by a lithium hydroxide aqueous solution and after that, drying and solidifying it to make it into a powder in which transition metals are made to adhere to manganese dioxide and mixing lithium carbonate with it and heat-treating its mixture. |
